Role of the renal nerves in the natriuresis of l-nmma infusion in
shr and wky rats.
Khraibi, Ali A.
Department of Physiology and Biophysics, Mayo Clinic and
Foundation, Rochester, Minnesota 55905
APStracts 2:0015F, 1995.
The purpose of this study was to determine the role of the renal
nerves in the natriuresis and diuresis that is observed with the
systemic infusion of a high dose of NG-monomethyl-L- arginine (L
-NMMA) to inhibit nitric oxide synthesis in the Okamoto spontaneously
hypertensive rat (SHR) and the Wistar-Kyoto (WKY) rats. All rats in
this study underwent a unilateral nephrectomy approximately two weeks
prior to the acute experiment. On the day of the acute experiment,
renal denervation of the remaining left kidney was performed in one
group of SHR (n=6) and one group of WKY rats (n=9). Another group of
SHR (n=6) and WKY rats (n=10) had an innervated kidney. A control
clearance period was taken, and then an L-NMMA (15 mg/kg bolus
followed by 500 g/kg/min continuous infusion) infusion period
followed in all four groups of rats. In the innervated SHR and WKY
rats, the increases in fractional excretion of sodium (FENa) were
5.110.70% and 3.580.38% respectively with the infusion of L-NMMA and
were associated with significant increases in fractional excretions
of phosphate (FEPi; 18.18+/-5.33% and 6.34+/-2.29% respectively)
suggesting a reduction in proximal tubule reabsorption. In the SHRs
with acute renal denervation, FENa was significantly increased by L-
NMMA, however, FENa was significantly reduced (2.030.70%; P<0.05) in
comparison with innervated SHRs and was associated with no increase
in FEPi (FEPi =-0.72+/-1.23%). In contrast, the natriuretic
(FENa=2.880.75%; NS) and phosphaturic (FEPi=5.04+/-3.40%, NS) responses
to L-NMMA infusion were similar in WKY rats with acute renal
denervation in comparison with innervated WKY rats. These results
suggest that in the SHR the inhibition of reabsorption by the
proximal tubule with L-NMMA infusion requires the presence of the
renal nerves and that the natriuretic and diuretic responses to
nitric oxide synthesis inhibition are partially dependent upon renal
innervation.
Received 12 September 1994; accepted in final form 5 February
1995.
APS Manuscript Number F312-4.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 February 1995.